Preheat the oven to 350 degrees. Spray an 8-inch round cake pan with cooking spray. Line the bottom of the pan with parchment paper, then generously spray the pan with cooking spray again. Set pan aside.

Place the cream cheese and 3/4 cup of blueberries in the bowl of a food processor and puree until well combined. Scrape the mixture into a large mixing bowl and add the sugar and flour. Beat with an electric mixer set to medium. Beat in the eggs and egg yolk one at a time, mixing until just incorporated. Scrape down the sides and bottom of the bowl. Turn mixer to low speed and beat in the sour cream, heavy cream, vanilla, and salt until smooth.

Pour batter into the prepared pan and smooth the top. Set in a roasting pan (or any large baking pan) and carry to the oven. Pour a couple inches of water into the pan, then carefully transfer to the oven. (Alternatively, you can place the pan in the oven and fill it there.) Bake 34 to 40 minutes, until the center of the cheesecake barely wobbles.

Remove from the oven and immediately run a knife between the cake and the edge of the pan. Cool cheesecake to room temperature. Once cooled, cover loosely with plastic wrap and refrigerate overnight.

After the cheesecake has refrigerated, dip the pan in a bowl of hot water for about 15 seconds. Run a knife several times around the edge of the cake, then set a large plate or a cake circle on top of the pan. Invert the cheesecake onto the plate. Keep refrigerated until you’re ready to assemble your layer cake.

Preheat the oven to 350 degrees. Spray 2 8-inch round cake pans with cooking spray and line the bottoms of the pans with parchment paper. Spray the paper with cooking spray, then lightly dust the pans with flour. Set aside.

Combine the cake mix, pudding, eggs, butter, water, and lemon zest in a large mixing bowl and beat with an electric mixer for 2 to 3 minutes, until well combined. Divide batter evenly between the prepared baking pans and bake 28 to 34 minutes, until a cake tester inserted into the center of the cakes comes out clean.

Remove from the oven and let cakes cool in pans for 10 minutes, then remove to a wire rack to cool completely before assembling your cake.

Combine the cream cheese and butter in the bowl of a stand mixer fitted with the paddle attachment and beat on medium until very creamy. Turn mixer to low and gradually beat in 3 cups of powdered sugar, then add the vanilla and salt and mix until incorporated. Turn mixer to medium and beat until creamy. If frosting is too thin, add additional powdered sugar as necessary. (If you add too much powdered sugar you can thin your frosting with milk or heavy cream.)

Place one of the lemon cake layers on a cake circle or cake stand and spread a thin layer of frosting over the top. Carefully top with the blueberry cheesecake layer. Spread a thin layer of frosting over the cheesecake and top with remaining lemon cake layer. Frost the cake with the remaining frosting and decorate as desired. Serve and enjoy.